Recently, naringin (NAR; 4',5,7-trihydroxyflavanone-7-rhamnoglucoside) has been shown to have cardioprotective properties. However, the specific mechanisms underlying its cardioprotective effects remain unclear. In this study, we aimed to investigate the cardioprotective effects of NAR and the possible underlying molecular mechanisms in cardiomyocytes using high glucose (HG) to induce apoptosis in H9c2 cells. The effect of NAR on apoptosis was assessed by Annexin V and propidium iodide staining, and by determining the levels of active caspase-3, -8 and -9. The effect of NAR on mitochondrial dysfunction was assessed by the loss of mitochondrial membrane potential (MMP). Our results demonstrated that exposure to HG induced apoptosis and mitochondrial dysfunction in cardiomyocytes. Treatment with NAR significantly increased MMP and inhibited the activation of caspase-3, -8 and -9. NAR attenuated the HG-induced p38 and p53 phosphorylation, decreased mitochondrial Bax and Bak expression, prevented the release of cytochrome c and increased Bcl-2 expression. Pre-treatment with SB203580, a p38 inhibitor, also suppressed p53 phosphorylation and prevented the loss of MMP, as well as apoptosis in the HG-treated H9c2 cells. Taken together, these data demonstrate that NAR inhibits HG-induced apoptosis by attenuating mitochondrial dysfunction and modulating the activation of the p38 signaling pathway.